Operating instructions

25-2
SCSI REFERENCE 1012975
CHAPTER 25—WRITE BUFFER (3Bh)
Be sure to heed the following cautions when issuing the WRITE BUFFER
command to update the microcode stored in the autoloader’s flash EEPROM.
When the WRITE BUFFER command is used to update the microcode, the
following actions occur:
1.
1.1.
1. If this was not the last or only WRITE BUFFER command, the autoloader
writes the microcode data to the buffer, returns Good status, and goes to the
Bus Free phase. Then, it waits for the next WRITE BUFFER command.
Otherwise, it goes to step 4.
2.
2.2.
2. When the autoloader receives the next WRITE BUFFER command, it
repeats steps 1 and 2.
3.
3.3.
3. When the data from the last or only WRITE BUFFER command has been
transferred, the autoloader disconnects from the SCSI bus.
4.
4.4.
4. The flash EEPROM is erased and reprogrammed with the new microcode.
After the flash EEPROM is programmed with new microcode, part of the
nonvolatile memory is erased. Because the cartridge inventory is stored in
this nonvolatile memory it is erased during the reprogramming process.
5.
5.5.
5. The autoloader reconnects to the SCSI bus and returns Good status if the
command was successful.
6.
6.6.
6. A Unit Attention condition is set for all hosts. The sense data indicates that
the microcode has changed.
7.
7.7.
7. The autoloader performs its normal power-on self test and reestablishes the
cartridge inventory.
Caution
 The WRITE BUFFER command allows you to load new microcode over the SCSI
bus into the autoloader’s flash EEPROM. It is not intended to be used for testing
autoloader functionality (that is, do not issue this command unless you are
actually loading new microcode).
 Because of memory limitations, the autoloader cannot validate the new
microcode data before erasing and reprogramming the flash EEPROM. If the
checksum calculated by the autoloader does not match the embedded
checksum, the autoloader continues executing from the Boot Block code. As a
result, you will only be able to issue a limited number of SCSI commands
successfully: REQUEST SENSE, INQUIRY, READ BUFFER, and WRITE BUFFER.
 Do not load microcode from one model of autoloader into another. (For
example, do not load microcode from an VXA-2 1x10 PacketLoader 1U into the
Magnum 1x7 LTO Autoloader or vice versa.)
 Be sure that the autoloader is reserved for the initiator’s exclusive use while the
WRITE BUFFER command is executing.
 Do not power off or reset the autoloader while this command is executing.